


Just The Beginning

by Werepirechick



Category: Teenage Mutant Ninja Turtles (TV 2012), Teenage Mutant Ninja Turtles - All Media Types
Genre: ....that i'm willing to admit i ship, Canon Compliant, F/M, I Will Go Down With This Ship, M/M, Multi, One Shot, Polyamory, Slow Burn, april is literally psychic and done with this triangle bs, casey's just waiting for his geniuses to figure things out, donatello is an insecure child who thinks the worst of everything, for the tmnt flashfic event on tumblr, it's the best poly in tmnt
Language: English
Status: Completed
Published: 2016-06-28
Updated: 2016-06-28
Packaged: 2018-07-18 18:56:17
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,826
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7326418
Author URL: https://archiveofourown.org/users/Werepirechick/pseuds/Werepirechick
Summary: <blockquote class="userstuff">
              <p>April wasn't sure when it started, maybe when Casey joined their small group of mayhem.</p><p>Casey can see what's happening, can't control it, and doesn't care that he can't.</p><p>Donatello is sure this'll tear them apart, and that it's all his fault.</p><p>(Or three kids fall in love and don't realize it's mutual.)</p>
            </blockquote>





	Just The Beginning

**Author's Note:**

> I wrote this like not a week into June and then sat impatiently for today to happen.
> 
> I'm forever shipping garbage, and this is one of my many ships from TMNT. I'm a super fluid shipper, and I started shipping these three together because of an extremely well written fic. Write a pairing well enough, whether it just two or more, and you'll probably be able to convince me of anything.
> 
> I'm hoping I drag some more people into the trash along with me.
> 
> Enjoy (ﾉ◕ヮ◕)ﾉ*:･ﾟ✧

 

 

April isn’t sure when it started. Maybe at the farm house, probably before.

No, it was definitely before that. It started when Casey first came into their small group of insanity. At the time, April had known for a long while how Donatello felt for her. His awkward flirting attempts, combined with his unsubtle fawning over her; his feelings weren’t hard to miss. Casey’s presence threw a wrench into that.

April didn’t lie to herself; she was flattered how much attention Donnie devoted to her. But… he was still a mutant turtle at the end of the day; still not at all a human. Casey was a human though, and obviously interested in her. Sure, they didn’t have a ton in common, but Casey did his best to make up for it with enthusiasm for what they did.

It didn’t change that Donnie could get on her level though, with math and physics; things Casey wouldn’t touch with a ten foot pole. The long conversations they had in his lab, about school work and scientific theory, were some of her favorite past times.

Donatello was awake every night, and she’d call him whenever she couldn’t sleep. Even in the dark months with her father was missing, he’d made it seem all okay; that they’d figure things out. She found herself wrapped up into the fold with his family, welcome and at home. He never made her feel left out, and frequently brought her mood up. Donnie was funny and articulate, and always available. His affections for her, not unwelcome but not exactly something she was ready for then, never put a damper on things. Even if she never acknowledged them, April felt Donnie would stay with her regardless; he was always too generous for his own good with her.

With Casey though, she had opportunities to feel normal even just for a little while; even if Casey wasn’t normal in the least. His quirks were many, but those many were endearing. Constant casual pickup lines aside, Casey was a great guy to be around. He was goofy, scrappy, and always up for an adventure. And when _she_ wasn’t up to adventures, he watched movies with her or went for long rambling walks. He was the worst and best distraction from the mayhem of life, by causing his own. Casey never once lied about who he was, completely honest in a very refreshing way.

Between both of them flirting with her and genuinely trying to be the right guy, she was stuck with a choice; the worst kind of choice.

She could choose Casey, who was as close to normal as she could get these days; who she could go to movies with, and walk down the halls of their school hand in hand with. The guy who sat with her at lunch and let her complain all she wanted, and then offered a game of hockey to work out the frustration. He was full of himself and brash with his actions, but he was sincere as they came. In his whirl wind way of living, he always managed to draw her in and make her laugh; even on her worst days. He was a safe choice, a _normal_ choice, in the sea of strange her life had become.

Or she could choose Donnie, the sweet genius who lived underground. Donnie, who always had a moment for her, to talk about anything for as long as she wanted; who went out of his way to include her, defend her, and was interested in everything she was. Donnie who was a know-it-all and a sarcastic asshole, but somehow managed to be the kindest person in her life. He was an individual with a hundred restrictions, but one that had all the will to work around them. He was a difficult choice, too many things they could never do, too many dangers to count. But he’d always be there for her, no matter what.

And even with the rivalry between them, her two boys grew closer in their own friendship; built on insults and rough housing. She watched them go from bitter enemies to mock fighting friends. With every trial they faced, won against and lost, she and the two of them grew closer.

Words with cutting edges dulled over time, until it was just another way for them to communicate. Glares lost their heat, and fists that connected left only light bruises. They stopped hating, and found something between it and fondness.

Without her in the mix, there wouldn’t have been anything preventing them from getting on like a house on fire.

Now, they were impatient, wanting answers, but not pushing her for them. She had to choose, she had to reject one of them. But every time she was sure of herself, her confidence would waver, and she’d go back to waffling between them.

_(There was a third option though, one she couldn’t bring herself to even think about yet. Too risky, too unlikely, almost for sure to drive them both away from her.)_

She turned a blind eye to the looks they gave her, and each other, and put off the decision for as long as she could stand the guilt of not deciding.

 

 

 

 

Casey never pretended he knew what was happening, he sort of just let it roll as it went. It didn’t take a genius to realize things had snowballed pretty quickly.

He’d fallen in with the turtles because of April, and he’d fallen in with April because of his shit work ethics. Not a bad turn of events, considering he had a fiery lady in his life and four kickass buds he could tussle with whenever.

Somewhere along the way, it got complicated. He’d had interest in April since the beginning, she was smart in ways he wasn’t and full of hidden fire. She made him want to be better, work harder in school and at least try to be an upstanding guy. Sure he failed both pretty often, but he tried and that’s all she asked of him. His interest in April though, brought the complication he hadn’t expected. A certain nerdy turtle with a vendetta against him from the get go.

Donatello made things difficult for both of them; their mutual interest in April threw the possibility of friendship out the window the first night they met. Casey was never one to back off from a fight though, and he didn’t start then. Donnie might have been able to run circles around him with words and equations, but Casey had the advantage of being with April at school, and of being an actual human. When their relationship started, it was all pissing contests and underhanded insults.

But even with the bad blood between them… Casey got to know the guy. Donnie was a serious dick sometimes, but he knew what he was doing with his inventions and sciences. That, mixed in with the fact that the turtle was able to bench press twice as much as him, made him into less of an enemy, more of a challenge to Casey. Casey had a thing for challenges.

April and Donnie were more similar than they looked at first glance, both were sharp with their words and even sharper with their minds. They out classed Casey completely in a lot of categories, and it drove him nuts to think even for a moment, they made a good pair without him around.

But with every insult he shot at Donnie, he got back just as good. Donnie never gave an inch, and neither did Casey. April humored their spats; letting them go at each other so long as they never crossed the line. It took weeks, but at some point Casey and Donnie found a balance between actual anger and something dangerously close to friendship. _(And later on, something more.)_

Casey never stopped to examine it, he never looked back on anything; the only way to do things was to go forwards full speed.

April was the most amazing girl he’d ever met, and the more they went up against the closer they got. She confused him often, but he kinda liked it; he liked it a lot actually, that she was so brilliant. And when she picked up martial arts? He could have sworn she was the one right then; beauty, brains, and deadly weapon skills. She might not be up to snuff yet, but he could definitely see her being able to kick his and everyone else’s butts one day.

Donnie on the other hand… he drove Casey to levels of frustration that no one else ever had. He always knew just how to get under Casey’s skin, just the right words to provoke him, and could take him in a fight with no trouble. But underneath all the antagonizing actions, Donatello knew when to back off or even to comfort in his own weird way. After New York was taken, the other teen distracted him with taunts during the day and never let him or April brood too much at night.

Casey wasn’t blind; he could see they were all sliding along thin ice. Lines were blurring and the slope getting steeper.

April was the ideal girlfriend, sweet but exciting, and an undercurrent of steel like strength. She was everything he’d ever wanted, even if she went over his head pretty often. Her multidimensional character wouldn’t ever get boring, and she’d surprise him constantly until the day they parted.

Donnie on the other hand, he amped Casey up and gave him outlet for his desire to fight. Always ready to go a round or two, always meeting Casey head on. Stubborn to a fault and a brain that never quit, Donnie was the perfect opponent. They had an understanding of where they could hit, and how hard; sparring verbally and physically when they really needed it. The turtle fit just right in a space Casey never knew he needed to be filled.

Two people, both important in a very similar way, and he didn’t know what to do with either. He was reluctant for the first time ever to make a move.

Instead of deciding for himself, he left it to April and Donnie. They were the smart ones after all, they’d figure it out.

 

 

 

 

Donatello, for a genius, took forever to see what was happening around him; between him and the other two. But he never claimed to be well versed in how relationships worked; no amount of research could fix that.

He’d been referred to as single minded and oblivious at times, and he agreed to a point. But he should have noticed, should have at least thought of it at some point in time; but he didn’t see anything until it was almost in his face.

Right from the first time he met her, April was someone he wanted in his life; someone he wanted to know everything about. She might have been the most complex person he knew, but categorizing what she was to him was simple. She was a girl, that he liked, and a great friend. Simple, straight forwards, and easy to understand; nothing complicated at all.

Casey though, Casey was nothing _but_ complications. The human got in his way every time he approached April, fought him on every little thing, and made chaos in all of Donnie’s neat little categories. Casey was incorrigible and it made Donnie see red every time he saw him when they first started hanging around each other.

When they went from that to being friends isn’t something Donnie can map, social interactions have always escaped him like that. But even so, shouldn’t he have seen this coming somehow? Predicted the result?

No, he couldn’t predict that even with all the flow charts in the world.

The world ended just as Donnie had started to get a grasp on what was happening, and then everything changed again. They lost everything in one go, and now their little group was all they had left. Even the hope of getting it all back didn’t change how lonely they were, floating in the cold reaches of space.

Being trapped in small space with only a few people makes you face things you don’t want to, and Donnie couldn’t escape that even with all the science he buried himself in.

He had to face it, had to look it dead in the eye and say it; the very clear lines of what he felt for who weren’t clear at all anymore.

As they’d traversed the universe, he withdrew into himself to think very long and very hard about what was happening.

He loathed admitting it, but the evidence was difficult to deny; especially when his own feelings were the evidence. Donnie’s affections for April had bled into his rivalry with Casey, making everything a muddle of emotions.

Oh Casey still drove mad, but he was _endearing_ for some god forsaken reason now. Donatello found his frustrations with the human becoming less because of their shared interest in April and simply because of Casey being Casey. A horrible realization and he almost hated himself for it, but he didn’t, he _couldn’t_ hate himself because of it.

Because Casey, for all the times he made Donnie’s temper rise, was enjoyable to be around. He satisfied Donnie's need for challenges, the desire to be better and _win_ ; something a third child rarely got to do. The human wasn’t helpful in the least for his work, but Casey gave him relief when Donnie's concentration slipped in his frustration. After a fight with Casey over something, anything, Donnie could focus completely on his tasks again with steady hands and a clear mind.

It was ominous that Donnie could put Casey and April on the same level now; two individuals he needed in his life no matter what.

For the whole time they were in space, Donnie ducked his head and did his best not to acknowledge his realizations; even when he could feel Casey watching him, or April’s aura of concern. He pretended very hard that the two of them didn’t exchange looks behind his back, that they could tell something was up.

If he did anything, _anything_ , to break the fragile links holding them together he’d never forgive himself. His feelings didn’t matter; he didn’t want to cost himself the two best people in his life. For all his plans and theories, he couldn’t figure out an ending where it worked out.

He wanted them both and it was horrible; horrible of him and horrible for them.

Donnie avoided everything, including both of them, until they saved earth. They could talk about things, _(they wouldn’t really, he wouldn’t let it get that far)_ , after they restored what they’d lost.

 

 

 

 

“We need to talk,” April said, throwing all of Donnie’s plans of avoidance under the bus.

“About what?” Casey asked, tossing a spare beaker between his hands. The three of them were in Donnie’s lab, where he and Casey had been hanging out before April had cornered them.

Donnie focused hard on the mutagen notes in front of him, pretending he didn’t know what was coming.

“About us, all of us,” April had that set to her features that meant there was no negotiating. Damn.

“…still not following,” Casey said, setting the empty beaker back onto the lab counter. He turned his whole body to face April, leaning on one elbow that sat near Donnie’s notes.

“I mean,” April waved her arms a bit, a small scowl on her face. “Us, as in what’s been going on between us.”

“You an’ me?”

“No, I mean you, me, _and_ Donnie,” April sent a look Donnie, which he continued to ignore. She sighed and walked over to the table to also sit down. Donnie shuffled his papers out of her way so she could prop her elbows up. She did, and folded her hands together too. “In case you forgot, I’m a psychic now. I can’t help but over hear what’s been going on.”

Casey sat up straighter looked between Donnie and April. “You mean…?”

“Yeah I do, Jones. Donnie knows what I mean too,” April looked at Donnie, who continued to stay silent. She shook her head and reached out to put a gentle hand on Donnie’s, who stopped breathing when she did. “Donnie, I might not be able to hear the actual thoughts, but I can feel what they mean. I know, okay? And I think Casey does too.”

Donnie withdrew his hand from hers and folded in on himself. He’d been afraid of this, but he also knew it had been coming for a long time. This was long since overdue.

“I’m sorry,” He said quietly. “I really am.”

“Dude, what?” Casey looked between the other two again. “What’s going on, why’s Donnie sorry?”

“Because I’m messing things up,” Donnie explained, a note of misery in his voice. “I didn’t mean to, but it happened without me noticing, and then I just-I couldn’t stop it. I tried, okay? I tried really hard.”

Casey rubbed the back of his head, feeling out of his depth yet again. “Still not following.”

April picked up Donnie’s building emotions and grabbed at him again. “No! No, that’s not what I meant Donnie!”

“Then what do you mean?” Donnie said, drawing back from her for the first time. “Do you want me to say it out loud? Do I have to spell it out?!”

“I’d like that,” Casey said, crossing his arms. “I’m lost as fuck here.”

“I like you both, okay?! That’s what she means!” Donnie exploded, slamming his hands against the table and making the two humans jump. “She means that I’m crossing the line and fucking things up for all of us!”

“No I don’t you idiot!” April shouted back, slapping her hands down as an echo of his. “Let me finish, okay?!”

“Whoa, jeeze, everyone calm down!” Casey raised his hands to placate the two of them, since when was he the guy who calmed things down? “What happened to talking shit out?”

“We’re _trying_ to talk it out, but I need you both to _listen_ for once!” April said. She pointed at Donnie with a stern look. “Let me talk, and _then_ you can have a freak out, okay?”

“This is about feelings, right?” Casey asked.

“Yes, Casey, we’re talking about our feelings,” Donnie said, shooting him a scowl. “I thought that was pretty obvious, considering what I just yelled.”

“Oh for the love of god,” April pinched the bridge of her nose.

“’Kay, just checking,” Casey crossed his arms again and leaned back. “I do too.”

“You do what?”

“Like you both, too. Nice to hear I’m not alone with that,” Casey said blithely.

“What.” Donnie said again.

“Donnie, he’s saying he likes us both; and I do too for that matter!” April threw her hands in the air. “We’ve been dancing around this since forever, and it’s been pretty obvious too! I’m really not sure how you missed that.”

“You-?” Donnie blinked, unable to compute what was happening. “You both, also…?”

“Yep,” Casey agreed.

“We really do, Don,” April smiled softly, bemused by his reactions and saddened by how disbelieving he was. “It’s just taken us forever to realize it.”

“Nah, I figured it out a couple months ago,” Casey shrugged, even as his two friends looked at him with incredulity. “What? I’m not the smart guy here, but I _do_ notice stuff. I just wasn’t gonna do anything until you two decided stuff.”

“And a couple months ago was…?” April prompted.

“Like, just after Northampton? Somewhere ‘round there?”

“So we could’ve… all this time?” Donnie asked, looking off kilter.

“Eh, probably, you were moving at your own pace though,” Casey shot Donnie a sly grin. “You two geniuses needed more time, an’ I’m a pretty patient guy.”

“Hardly,” Donnie said, resorting to familiar methods of talking by insult. “You can’t wait any better than Mikey can for pizza.”

“Well,” April said, clapping her hands together. “This has been very informative of how bad we are at communicating. At least it’s all in the open now.”

“I don’t believe this,” Donnie rubbed at his eyes. “I don’t believe this is actually a conversation that’s happening.”

“It took like eighty years, but here we are,” Casey said, still grinning.

“It definitely took us too long,” April huffed. She reached across the table and grabbed a hand from both Donnie and Casey; Casey completing the triangle by grabbing Donnie’s free hand. “Now that we’ve got this rolling along finally; how’s about talking a little more about how we feel? Cause I for one am very tired of pretending they don’t exist.”

Donnie opened his mouth to reply when the door to his lab crashed open and Raph and Leo went tumbling inside.

“Or we could talk later,” April amended, shaking her head.

“Yo, pizza’s here!” Mikey yelled over the shouting of his brothers from outside the lab. “Come an’ get it before it gets cold, it’s our first earth pizza in months!”

Donnie looked at his two elder siblings wrestling on the floor and sighed deeply. It figured that the moment they had things beginning to sort themselves out, they’d be interrupted.

April rubbed the knuckles his hand. “No worries, you two can come home with me tonight and we can talk over cocoa.”

“Sweet, I’m all for it,” Casey said, excited for alone time with his two favorite people.

Donnie nodded, turning his eyes back to the people holding his hands. “Yeah, I’ll tell Sensei I’ll be out late tonight.”

“Take back what you said about Mona!” Raph yelled at Leo, trying to hold the other in a head lock.

“You take back what you said about Karai!” Leo countered.

“She’s our sister you sick fuck!”

“Mona isn’t even her real name, asshole!”

Donnie let April and Casey’s hands slip out of his as they stood up to break up the fight. Their loss of warmth was unpleasant, but he took comfort that now he could do it again. Again, and again, and again hopefully.

His relief still had his bones loose and weak, and he had a bubbling feeling inside his plastron. He felt a giddy smile cross his face as he watched Casey haul Raph off of Leo, April reprimanding them both for being immature.

Not just one, but _both_ of them returned his feelings; he felt like someone had flipped his axis upside down.

“Holy shit,” He whispered under his breath. It would take a while for that to sink in.

“You coming, Donnie?” April asked him from the doorway. He hadn’t moved from the table yet.

He grinned at her and hurried to follow her out. Finally, things between them were clear again. Now that they had things out in the open, they could really start their relationships.

This was only the beginning.

 

 

**Author's Note:**

> *strikes a flashy pose* Well that certainly happened. 
> 
> Here's to hoping people besides my partner and I enjoyed this fic, I had a lot of fun making it.
> 
> I personally think canon would be 10000% better if we had ships other than just heteronormative ones. (If you can count them like that, since technically everyone's either an alien or a mutant.)
> 
> I'm also a huge sucker for weirdly functional polys and lookit that, here's one right here.
> 
> If you liked this, please go reblog it from my writing tumblr; It'll help get me noticed, and your under no obligation to follow me, though I'd like that a lot. Even just a like would help.
> 
> Thanks for reading!
> 
> (My blog for writing is onthespectrumwriting, look under the "my writing" tag or "capritello" tag.)


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